1. Field of the Invention
This invention is in the field of CRTs (cathode ray tubes) and more particularly to controls for providing signals and corrections for controlling the CRT display.
2. Description of the Prior Art
CRTs characteristically have display distortions including geometric, astigmatism, focus, shading and/or convergence distortions. As used herein, "geometric" corrections are those corrections necessary to place a point displayed on the screen at the exactly correct horizontal and vertical coordinates. Numerous efforts have been made to provide corrections and signals for distortionless CRT displays. The disclosures in the following U.S. Pat. Nos. are representative of such efforts: 4,095,137; 4,240,073; 4,386,345; and 4,410,841. While these systems attempt to provide distortion correction signals and distortionless signals based on data stored in memories, the manner in which the data are stored and/or used in the display control system limit the versatility and application of these systems.